1. Field of the Invention
The invention relates to apparatus for controlling the operation of a currency changer and, in particular, to an apparatus for controlling the operation of a currency changer including a paper currency acceptor.
2. Description of the Prior Art
Devices that perform one or more tests on U.S. bills or other paper currency to determine their genuineness in order to dispense change are well known in the prior art. Typically, in such devices, the paper currency being validated is moved over a path along which various optical, magnetic or edge sensing tests are performed. On failing any of these tests, the bill is moved along the path in a reversed direction to be returned to the user and no credit is given. For example, a bill is moved along a path at a uniform rate of speed past a pair of photocells spaced farther apart than the length of the bill. If both photocells are covered simultaneously, the inserted object is rejected, since it cannot be a genuine bill.
Such prior art validators are subject to tampering and defrauding. For example, strings are sometimes attached to currency which is provided to a change machine. After change is given, an unacceptable article is fed to the change machine. As the unacceptable article is being rejected, the user pulls the stringed article out simultaneously therewith. There is a need in the prior art for bill validators which prevent repeated withdrawal of stringed bills thereby preventing a user which tampers or defrauds a change machine from emptying the bill change machine of its change.